Pilot operated pressure-vacuum relief valves

ABSTRACT

An improved pressure vacuum relief valve having a pressure energized seat, a secondary seat with a stop adapted to be used with a pilot valve to relieve a vacuum condition and with two pilot valves to relieve pressure and vacuum conditions.

United States Patent Walter W. Powell Dennis L. I-lowland, both ofHouston, Tex. 808,797

Mar. 20, 1969 June 8, 1 97 1 Anderson Greenwood & Co.

Bellaire, Tex.

Inventors Appl. No Filed Patented Assignee PILOT OPERATEDPRESSURE-VACUUM RELIEF VALVES 5 Claims, 6 Drawing Figs.

US. Cl 137/489, 137/493 1nt.Cl .L..F16k 17/10, Fl6k 17/18 Field ofSearch 137/489,

References Cited UNITED STATES PATENTS 7/1928 McEwan 137/488 5/1953Teague..... 137/489X 8/1953 Ensign 137/489 9/1958 Lee l37/493X 1 H1969Powell 137/489 Primary Examiner-M. Cary Nelson Assistant Examiner-R. B.Rothman AttorneysJ. Vincent Martin, Joe E. Edwards and Jack R.

Springgate ABSTRACT: An improved pressure vacuum relief valve having apressure energized seat, a secondary seat with a stop adapted to be usedwith a pilot valve to relieve a vacuum condition and with two pilotvalves to relieve pressure and vacuum conditions.

PATENTEU JUN 81971 SHEET 1 OF 3 Wa/zer 14 Paws BY w W PILOT OPERATEDPRESSURE-VACUUM RELIEF VALVES SUMMARY The present invention relates toan improved relief valve and to a combination of relief and pilot valvessuitable for use to relieve vacuum conditions and to relieve bothpressure and vacuum conditions.

An object of the present invention is to provide an improved reliefvalve having positive sealing.

A further object is to provide an improved relief valve which canutilize pressure in its pressure responsive means to assure positiveseating under only minor pressure differentials.

Another object is to provide an improved relief valve and pilot valvecombination having improved protection for a container against vacuumconditions.

Still another object is to provide an improved combination of reliefvalve and pilot valves having improved protection for a containeragainst pressure and vacuum conditrons.

BRIEF DESCRIPTION OF THE DRAWINGS These and other objects and advantagesare hereinafter described and explained with reference to the drawingswherein:

FIG. I is a sectional view of the improved main relief valve and pilotvalve of the present invention for relieving against vacuum conditions.

FIG. 2 is a partial sectional view of the pilot valve.

FIG. 3 is a partial enlarged sectional view of the improved seating ofthe main relief valve.

FIG. 4 is an enlarged detail sectional view of the main valve memberillustrating the communication providing the improved pressure sealingof the present invention.

FIG. 5 is a schematic diagram of a combined relief valve and pilot valveused for relieving vacuum conditions.

FIG. 6 is a schematic diagram of a combined relief valve and two pilotvalves used for relief of both pressure and vacuum conditions.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The relief valve systemillustrated in FIG. 1 includes a main relief valve 10 and a pilot valve12 connected to provide pro tection against excess pressure. Ashereinafter explained, the same combination main relief valve 10 andpilot valve 12 may also be connected to provide vacuum protection, andwith two such pilot valves to provide both pressure and vacuumprotection.

The main relief valve 10 includes the body 14 having the ports I6 and 18with the seat 20 surrounding communication through body 14 between theports 16 and IS. The annular sealing surface 22 is defined by the bodyI4 immediately surrounding the seat 20 and the seat 20 projects slightlybeyond the plane of sealing surface 22 as shown. The main relief valve10 also includes a valve member 24, pressure responsive means 26connected to actuate the valve member 24 and a port 28 communicatingwith the chamber 30 defined by the body 14 and pressure responsive means26. As shown in FIG. I, the pressure responsive means 26 is a bellows 32and the chamber 30 is formed by the bellows 32 and the cover 34 which issecured to body 14. The port 28 is defined in fitting 36 which issecured to cover 34 and extends within the bellows 32 to receive theguide sleeve 38. Guide sleeve 38 is secured to the end of bellows 32secured to valve member 24 and extends axially within bellows 32 and isslidable in fitting 36 to guide valve member 24 in its movement. Fitting36 is provided with the holes 40 to provide communication into chamber30. The outer end of fitting 36 is internally threaded to receive thepipe 42 which extends to the pilot valve 12 as hereinafter explained.

The valve member 24 includes the circular plate 44 which is connected tothe inner end of bellows 32, the seating membrane 46, the membranesupport plate 48, the annular seal 50 and the annular stop 52. Bolt 54secures the seating membrane or diaphragm 46 and the support plate 48 tothe plate 44. The side of plate 44 facing diaphragm 46 defines anannular recess 56. Communication is provided from the interior of sleeve38 through the bushing 58 and plate 44 to the recess 56 so that domepressure (the control pressure maintained in chamber 30 by pilot valve12) is exerted on diaphragm 46. The outer periphery of diaphragm 46 issecured to plate 44 by the annular seal 50 and the annular stop 52. Seal50 includes an outwardly extending flange 60 which is positioned in therecess 62 in stop 52. As best seen in FIG. 3, the axially extendingportion of seal 50 extends beyond stop 52 so that as valve member 24closes, the seal 50 engages sealing surface 22 before stop 52 engagessealing surface 22.

Initial sealing of the valve member 24 on seat 20 is provided by thediaphragm 46. As shown in FIG. 3, the diaphragm 46 is urged by thepressure toward and around the projection forming seat 20. The arrowswithin recess 56 illustrate the pressure acting on diaphragm 46 toprovide sealing when seated.

The pilot valve I2 includes the body 64 having ports 66, 68 and 70 withvalve seat 72 surrounding communication between ports 66 and 70, thevalve member 74 movable to open and close flow through valve seat 72 andthe actuator 76 connected to move valve member 74 responsive to thepressures delivered thereto. Pressure from port 16 of main valve 10 iscommunicated through line 78 to port 68. Pipe 42 is connected into port66 so that pilot valve 12 controls the pressure within chamber 30 andtherefore the actuation of valve member 24.

Actuator 76 is provided with the case 80 and the diaphragms 82 and 84which together form the sensing chamber 86, the boost chamber 88 and theupper chamber 90. The diaphragms 82 and 84 are movable in the chambers86, 88 and 90 responsive to pressure differentials and are connected tovalve member 74 to thereby control the movement of valve member 74. Port92 communicates from port 68 to sensing chamber 86, line 94 connectsfrom port 96 to boost chamber 88 and upper chamber 90 is vented. Spring98 biases the diaphragms and valve member 74 toward seated position andis adjustable by rotation of screw 100. As best seen in FIG. 2, port 96communicates with both ports 66 and 68 at a position between fixedrestriction I02 and the variable restriction 104.

Thus, when the pressure in port 16 exceeds the maximum desired pressure,the pressure in sensing chamber 86 lifts valve member 74 off seat 72 torelieve the pressure in chamber 30 and thereby cause valve member 24 tolift off seat 20 to relieve the excess pressure in the container towhich valve 10 is connected. The reduction in pressure in port 16responsive to relieving is communicated to sensing chamber 86 causingpilot valve I2 to close, delivering increased pressure to chamber 30 tocause main valve 10 to close. When pilot valve 12 is open, flow occursthrough variable restriction 104 and through fixed restriction 102 toprovide two pressure drops so that the pressure at point 96 is below thepressure in port 68 and above the pressure in port 66. This intermediatepressure at port 96 is the pressure in boost chamber 88. The adjustmentof the variable restriction 104 controls the relative pressures inchambers 86 and 88 of actuator 76. With little or no restrictionprovided by this variable restriction 104, the pressure in the chamberswill remain substantially the same. Since the effective pressure area ofthe upper diaphragm is smaller than that of the lower diaphragm,pressure in the boost chamber 88 thereby decreases the net lifting forceof the pressure responsive means against the spring 98. Also, by varyingthis restriction to provide a maximum pressure drop, the net liftingforce on the diaphragms is increased as soon as there is flow in theline allowing the boost chamber 88 to be substantially reduced inpressure with respect to the sensing chamber 86.

The diagram of FIG. 5 shows the combination of a pilot valve P and arelief valve R connected to relieve a vacuum condition in tank T. Pilotvalve P controls the actuation of relief valve R by controlling thepressure in the chamber C of relief valve R. in the diagram, pilot valveP is the same as pilot valve 12 previously described and relief valve Rmay be the same as the main valve previously described or any othersuitable relief valve which functions responsive to the pressuredifferentials between the chamber C and the port in communication withtank T. The hookup of pilot valve P and relief valve R for such vacuumreliefservice is as shown in FIG. 5v

Port 166 is connected to chamber C by pipe 142. The vacuum conditions intank T are communicated to upper chamber 190 of actuator 176 by line109. Atmospheric pressure is delivered through check valve 111, port 168and port 192 to sensing chamber 186, through variable restriction 204and line 194 to boost chamber 188 and through fixed restriction 202 toport 166. Valve member 174 controlled by actuator 176 when engaging seat172 closes communication between ports 166 and 170. Line 113 connectsport 170 to the tank side port of relief valve R. Bypass line 115 withcheck valve 117 therein communicates between line 113 and pipe 142 sothat increases in pressure in tank T are communicated through lines 113,115, check valve 117 and pipe 142 to chamber C but reverse flow isprevented.

The vacuum relief of the combination shown in FIG. 5 functions to openrelief valve R allowing flow of external air at atmospheric pressureinto tank T whenever the vacuum condition in tank T exceeds the maximumdesired vacuum. The reduction in pressure is sensed in chamber 190 andwhen it exceeds the minimum desired pressure, the pressure differentialson actuator 176 opens valve member 174. This exhausts the pressure inchamber c allowing valve R to open.

From this, it can be seen that the pilot valve when connected as shownin FIG. 5 to the relief valve R causes the relief valve R to openallowing atmospheric air to flow therethrough into the tank T to relieveexcess vacuum conditions within the tank T. Also, whenever pressureabove atmospheric is present in the tank T, such pressure is conductedthrough the line 113, the bypass 115, the check valve 117 to the chamberC. This assures that the relief valve R remains closed since theeffective pressure area of the relief valve responsive to the pressurein chamber C is greater than the effective pressure area of the reliefvalve responsive to the pressure within the port connected to tank T,

As is shown in FIG. 6, the pilot valves P and P are connected to therelief valve R to provide relief for both pressure and vacuum conditionswithin the tank T. The pilot valve P functions to relieve the pressurewithin the chamber C of relief valve R whenever pressure conditionswithin the tank T exceed the preselected maximum desired pressurethereby allowing relief of pressure through relief valve R. The pilotvalve P" is connected to relieve the pressure in the chamber C allowingthe relief valve to open to permit the flow of air into the tank Twhenever the vacuum conditions exceed a preselected maximum vacuum or apreselected minimum absolute pressure.

As shown, the pilot valve P is connected with respect to the reliefvalve R in a manner similar to the connection illustrated in FIG. 1 andthe pilot valve P" is connected to the relief valve R in a mannersimilar to the connection illustrated in FIG. 5. Since two pilot valvesare being used, the connections to the chamber C of valve R is themanifold 242 connecting to the port 366 of the pilot valve P and to port266 of the pilot valve P. The line 209 connects from the tank T to thepilot valve P to communicate vacuum conditions to the upper or thirdchamber 290 of pressure responsive means or actuator 276. Atmosphericpressure is conducted to the chamber 286 through check valve Zlll, port268 and port 292. Pressure is communicated from the port 268 throughvariable restriction 304 through the line 294 to the chamber 288. Port266 and manifold 242 are in communication with port 268 through variablerestriction 304 and fixed restriction 302. The communication betweenport 266 and port 270 is surrounded by the valve seat 272 and flowtherethrough is controlled by valve member 274 responsive to themovement of the pressure responsive means 276. Lines 378 and 213communicate from the inlet of relief valve R to the port 270.

The pilot valve P having its port 366 connected to the chamber C ofrelief valve R by the manifold 242 is also connected to the inlet of therelief valve R by the line 378 which communicates through the checkvalve 321 to the port 370. This pressure is communicated through thepassage 392 to the chamber 386 of pressure responsive means or actuator376. Pressure is communicated from the port 370 through the variablerestriction 404 and the line 394 to the chamber 388 of the means 376.Communication from port 370 to port 366 extends through the variablerestriction 404 and the fixed restriction 402. The valve seat 372surrounds communication between the port 366 and the vent port 370 andflow therethrough is controlled by the valve member 374 responsive tothe movement of the pressure responsive means 376.

With the combination of the two pilot valves P and P connected as shownin FIG. 6 to control the relieving operation of the main relief valve R,relief of pressure conditions exceeding a preselected maximum desiredpressure in tank T and exceeding preselected maximum vacuum or minimumabsolute pressure condition in tank T are relieved. Whenever vacuumconditions exceed the preselected maximum vacuum, such conditions arecommunicated through line 209 to the chamber 290 in the actuator 276causing the valve 274 to unseat. When valve 274 unseats, fullcommunication is established to the inlet of relief valve R from thechamber C through the manifold 242, the ports 266 and 270, the line 213and the line 378. This causes the pressure in the chamber C to bereduced to the pressure existing within the tank T. With a pressure lessatmospheric in the chamber C, the atmospheric pressure from the port ofvalve R which is exposed to atmosphere causes the valve R to openallowing flow of air into the tank T to relieve the vacuum conditionsexceeding the preselected maximum desired vacuum conditions.

Whenever pressure in the tank T exceeds the preselected desired pressuretherein, such pressure is communicated through line 378, check valve321, port 370, passage 392 to the chamber 386 to cause the pilot valveto open placing the chamber C in communication with the vent port 370through the manifold 242, the port 366 and the valve seat 372. With thepressure vented from chamber C, relief valve R opens responsive to thepressure conditions within its inlet to allow fluids from tank T to venttherefrom. As may be seen, whenever relief valve R is open eitherresponsive to pressure or vacuum conditions as soon as adequate reliefhas been achieved, the relief valve R closes responsive to an increasein pressure delivered to the chamber C from the controlling one of thepilot valves P and P.

From the foregoing, it can be seen that the present invention providesan improved combination for the control of vacuum and for the control ofboth pressure and vacuum conditions by use of a single means reliefvalve. Additionally the present invention provides as an improvedcombination, a main relief valve having improved sealing on its seatincluding both a main pressure responsive sealing responsive to thepressure in the control or dome chamber of the relief valve and alsosecondary sealing associated with a limit scope on the valve member.

lclaim:

1. An apparatus for relieving excess vacuum conditions within acontainer comprising,

a main valve having a first port adapted to be connected to thecontainer to be protected, a second port, a valve seat surroundingcommunication between said first and second ports, a valve membermounted for movement in said valve and a pressure responsive meansconnected to said valve member to move said valve member into and fromengagement with said valve seat to close and open flow through said mainvalve,

a pilot valve having a first port connected to said pressure responsivemeans of said main valve, a second port connecting to the atmosphere,and a third port in communication with the first port of said mainvalve, a valve seat surrounding communication between said first andthird ports, a valve member, and pressure responsive means connected tomove said valve member to and from enports, a valve member, and pressureresponsive means connected to move said valve member to and fromengagement with said valve seat,

means for communicating vacuum conditions and atgagement with said valveseat, 5 mospheric pressure to said pilot valve pressure responsive meansfor communicating vacuum conditions and atmeans h eby h a pr selectedmaximum vacuum mospheric pressure to said pilot valve pressureresponsive Condition Occurs in Said container Said Pilot Valve meanswhereby when a preselected ma i u vacuum member is unseated to allowpressure from the first port condition occurs in said container, saidpilot valve said Plain to equalize through said Pilot Valve member isunseated to allow pressure from the first port Frsssure responsive meansto of said main valve to equalize through said pilot valve thereby allowF f f to P to reheve with Said valve pressure responsive means to herebythe excess vacuum condition within said container, and allow said mainvalve member to open to relieve the exan apparamS mc|ud'ng 6658 Vacuumcondition with said container and a second pilot valve having a firstport connected to said an apparatus including l pressure responsivemeans of said mam valve, a second a bypass line connecting between saidpressure responsive the atmosphere a thlfd m means of said main valveand said main valve first port, commumcauon wlth.sald first of.sald mamvalveia and valve seat surrounding communication between said a checkvalve in said bypass to allow flow only toward said first second ports avalve member and Pressure main valve pressure responsive means whereby apositive responsive means Connnected to Sald valve member to and fromengagement with said valve seat, pressure above atmospheric pressure atsaid first port of and Said main q j dfanvergd to Said pressureresponsive means for communication pressure conditions to said means toma'mam mam vlve f second pilot valve pressure responsive means wherebyAn w accordmg clam mcludmg mean? when a preselected maximum pressurecondition ocnected to said pilot valve second port to allow flow thereinand curs in Said container, Said Second pilot valve member prevent flowoutwardly" I is unseated to allow pressure from the pressure respon- 1An apparatus for T excess vacuum commons sive means of said main valveto bleed through said first w'thm a comamer 9 port and said second portto atmosphere and thereby a main Valve havmg a first P adapted to beconnected to allow said main valve member to open to relieve the exthecontainer to be protected, a second port, a valve seat Cass pressurewithin said container surrounding communication between said first and4. An apparatus according to claim 3, including a check second ports, avalve member mounted for movement in valve connected into said firstpilot valve second port to allow said valve and a pressure responsivemeans connected to now on y in i por said valve member to move saidvalve member into and An pp ra ing to laim 4, including a check fengagement i h id valve seat to close d Open valve in the communicationbetween said second pilot valve fl w h h id i valve, third port and saidmain valve first port to prevent flow a first pilot valve having a firstport connected to said prestherethrough to said main Valve first P andto allow flow sure responsive means of said main valve, a second porttherethrough f said main Valve first P E to said second connecting tothe atmosphere, and a third port in commu- 4O Pllot Valve P" y secondP1lot Valve senses nication with the first port of said main valve, avalve seat Press0 at mam Valve first P surrounding communication betweensaid first and third

1. An apparatus for relieving excess vacuum conditions within a container comprising, a main valve having a first port adapted to be connected to the container to be protected, a second port, a valve seat surrounding communication between said first and second ports, a valve member mounted for movement in said valve and a pressure responsive means connected to said valve member to move said valve member into and from engagement with said valve seat to close and open flow through said main valve, a pilot valve having a first port connected to said pressure responsive means of said main valve, a second port connecting to the atmosphere, and a third port in communication with the first port of said main valve, a valve seat surrounding communication between said first and third ports, a valve member, and pressure responsive means connected to move said valve member to and from engagement with said valve seat, means for communicating vacuum conditions and atmospheric pressure to said pilot valve pressure responsive means whereby when a preselected maximum vacuum condition occurs in said container, said pilot valve member is unseated to allow pressure from the first port of said main valve to equalize through said pilot valve with said valve pressure responsive means to thereby allow said main valve member to open to relieve the excess vacuum condition with said container, and an apparatus including a bypass line connecting between said pressure responsive means of said main valve and said main valve first port, and a check valve in said bypass to allow flow only toward said main valve pressure responsive means whereby a positive pressure above atmospheric pressure at said first port of said main valve is delivered to said pressure responsive means to maintain said main valve closed.
 2. An apparatus according to claim 1, including means connected to said pilot valve second port to allow flow therein and prevent flow outwardly.
 3. An apparatus for relieving excess vacuum conditions within a container comprising, a main valve having a first port adapted to be connected to the container to be protected, a second port, a valve seat surrounding communication between said first and second ports, a valve member mounted for movement in said valve and a pressure responsive means connected to said valve member to move said valve member into and from engagement with said valve seat to close and open flow through said main valve, a first pilot valve having a first port connected to said pressure responsive means of said main valve, a second port connecting to the atmosphere, and a third port in communication with the first port of said main valve, a valve seat surrounding communication between said first and third ports, a valve member, and pressure responsive means connected to move said valve member to and from engagement with said valve seat, means for communicating vacuum conditions and atmospheric pressure to said pilot valve pressure responsive means whereby when a preselected maximum vacuum condition occurs in said container, said pilot valve member is unseated to allow pressure from the first port of said main valve to equAlize through said pilot valve with said main valve pressure responsive means to thereby allow said main valve member to open to relieve the excess vacuum condition within said container, and an apparatus including a second pilot valve having a first port connected to said pressure responsive means of said main valve, a second port connecting to the atmosphere, and a third port in communication with said first port of said main valve, a valve seat surrounding communication between said first and second ports, a valve member, and pressure responsive means connnected to move said valve member to and from engagement with said valve seat, and means for communication pressure conditions to said second pilot valve pressure responsive means whereby when a preselected maximum pressure condition occurs in said container, said second pilot valve member is unseated to allow pressure from the pressure responsive means of said main valve to bleed through said first port and said second port to atmosphere and thereby allow said main valve member to open to relieve the excess pressure within said container.
 4. An apparatus according to claim 3, including a check valve connected into said first pilot valve second port to allow flow only into said port.
 5. An apparatus according to claim 4, including a check valve in the communication between said second pilot valve third port and said main valve first port to prevent flow therethrough to said main valve first port and to allow flow therethrough from said main valve first port to said second pilot valve third port whereby said second pilot valve senses the pressure at the main valve first port. 